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Green Roof in Edmonton

The roof of the Williams Engineering Building is going to have a new roof installed in early April this year. WEC is working with novaNAIT who will use the roof as a teaching and demonstration pilot project for the next couple years. NAIT students will have a few test plots on the roof to test different plantings.

Eventually the roof will also have a weather station to help NAIT students correlate the changing weather to the green roof conditions.

Something like that would require among other things: sufficient depth of planting medium, appropriate irrigation, and necessary drainage, not to mention the adequate infrastructure to support people on the roof (if it is to be an inhabitable amenity space for example, the membrane must be treated differently. Additionally, simple things like access and fire / health /safety have to be considered. The rules are obviously much different if the space is only intended to be accesses for mechanical / maintenance purposes).

A greenroof like the one depicted above could probably work with a relatively minimal amount of soil, or perhaps just a layer of rockwool / mineral fibre on top of the membrane. An 'intensive' system however would be far more substantial.

The downtown Vancouver Library has a green roof, though there is no public access to it (stupid). Also one of the major hotels in the core have a section of green roof and grow their seasonal herbs and veggies. (I seem to recall it was the Four Seasons but don't quote me)

The new Fort Edmonton Administration building is supposed to have a green roof when it is built. At least that is what the funding announcment said.

Being that it's Fort Edmonton and I am thinking of a historical context. isnt a Admiistative Building just a fancy name for a Sod Roofed house? Kidding! This is the prairies after all, if they re-worked that idea into a modern context it would be keeping in theme with the Park?

i agree with you completely ChrisD - but so are the "non-vegetative" green roofs. as for whether vegetative is better than non, there are advantages to both in differenct circumstances. i was simply pointing out the difference, not taking sides.

a green roof is generally considered to be a roof that is "environmentally friendly" as opposed to the traditional asphalt/tar and gravel technology ChrisD mentioned. examples would include the one that started this thread that use vegetation whether active or passive; cool roofs whose high reflectivity reduces the urban heat effect of solar radiation; roofs used to house solar thermal panels; and roofs used to house photovoltaic panels.

The new Fort Edmonton Administration building is supposed to have a green roof when it is built. At least that is what the funding announcment said.

You're correct. This was the initial plan for the administration building/point of entry at FEP, the building itself forming a kind of man-made hill that would blend seamlessly into the rest of the landscape (kind of like the Bentley plant in Crewe, England). However, costs escalated beyond what the city could afford and a different, entirely conventional vegetative roof-less plan was adopted. It's nearing completion now with move in slated for July.

I'm excited to see what kind of success the vegetative roof on the Williams Engineering building enjoys...hopefully it proves that green/vegetative roofs are the way of the future and not just a component of a fleeting "green fad".

Makes the look down that much better for Telus building people and Hotel Mac guests who have windows facing it. Gets rid of a little grey.
I would love to do that with our building, but alas I don't think the owner is interested.

My antidepressent drug of choice is running. Cheaper with less side effects!

all the concrete downstairs doesn't look so bad from that angle. Kudos to W.E on their green-roof. I wish Scotia Place would consider doing something like this over the main entrance to their building.

^ I am not suggesting that there won't be (or are not already) any success stories.

I am am just hedging that as they become more popular and ultimately more dumbed down by the developers and designers, less maintained by the building owners and so on the more we will see the predictable problems and outcry over maintenance, replacement and damage repair costs.

I am already shaking my head at lack of thought that is going into the details I am seeing on stuff being proposed. I don't expect it to improve much until the people responsible experience some problems first hand but when that happens the consumer confidence will already have been shaken.

And none of that even touches on the extremely marginal benefits of have a green roof on the average project to start with.

i think this is one of those things that makes sense because it can be a "right thing to do" for the building's occupants and for those that look at it (much like good architectural design and urban edges also have "value" even though they don't have a "payback period") and for those that live in the cities that utilize them.

however, i would doubt whether there is as much - if any - actual payback from a living/green roof as there would be from a well insulated highly reflective roof. and when you factor in the substantial additional roof loading that is needed not only for the soil but for the retained water and ice that accompanies it and the additional structural requirements that may be needed all the way through to the building's foundations and pay for them all you may never see a payback.

that doesn't mean green roofs shouldn't be done, just to note that there is a tendency today to "oversell" things because they're "green" and "more efficient" and "they pay for themselves" when that shouldn't necessarily be the reason to choose them. because when they don't perform the way they were oversold or save money the way they were represented, they lose value that shouldn't have been promised in the first place when they should be just as valuable without them.

^it is part of a much larger solution to the above and if incorporated more often would positively contribute to a many faucets of our climate woes.

OK, but how?

Even more specifically, 'how' as it applies to Edmonton and Edmonton's climate?

Worldwide, buildings produce approximaely 40% of total carbon emissions and 80-85% of a buildings energy usage comes from heating, cooling and hot water.

Green roofs reduce the overall energy consumption of a building; while their effect may be more prominant in warmer climates, this does not preclude their benefits in a place like Edmonton. The amount of research in cold climate green roofs is relatively minimal, however, research is ongoing and is displaying the benefits of such roofs.

Also, while many may consider the benefits of a few green roofs to be a drop in the bucket, don't forget that it was the cumulative effects of many drops in the bucket that got us into our current dilemma.

^principally in an R value increase in your roof insulation to reduce cooling needs in summer and more importantly heating needs in winter.

The thing is that the added R value from a green roof is less efficient per inch than the added R value from simply adding more insulation at the same depth.

For example if you had an R-18 roof (usually the baseline roof R-value of the roofs referenced in in the green roof studies) and added a 6" deep green roof, you would reduce the heat loss by 25%. Not bad.

Now if you added a further 6" of insulation to an R-18 roof you would reduce the heat loss by about 66%.

Added to that there are no addition costs due to structural concerns as well as there are no irrigation concerns (which in itself is crazy when you consider the whole green roof concept is supposed to be about protecting the environment).

You realize that virtually every residential building built in Alberta is likely done with PEX right? It's basically the exact same thing, but with a slightly different plastic.

Yup, I'm well aware of what's used in the industry.

Basically but not exactly is the key. If Poly-B wasn't problematic then there would be no 'basically...but with a slightly different plastic' and Poly-B would still be in use.

Most of the problems with poly-b were overblown in Alberta, really. There were very few failures because of the fittings used and our climate. Where there were a lot of failures was where plastic fittings were used, or in very warm climates like Arizona where the water lines were run in attic spaces where the temperature would exceed the rating of the pipe (pressure rating goes down as temperature goes up).

Most local opposition to poly-b was simply "old-school" plumbers who simply didn't like flexible tubing in general, and for some decent reasons (looks like crap, easier to puncture during or after construction, and so on).

World Green Roof Congress 2010

Hi, if you really are into this stuff and if you want to know whats going on all over the world regarding green roofs, you may want to check the next websites.

The first is about the World Green Roof Congress (WGRC) 2010 in London which just ended last sept 16. The second one is about the upcoming WGRC 2010 in Mexico city which will go from oct 7-9. The last one is about the Green Roofs for Healthy Cities, a Canadian organisation based in vancouver. Its name tells pretty much all what it is about.

I noticed in Toronto that many of the condo buildings have large trees, shrubs, etc on the roof. I don't know if I would go so far as to call them green roofs... but it was very common to have LARGE trees etc up on the upper floors. Why haven't developers caught on to this here?

I noticed in Toronto that many of the condo buildings have large trees, shrubs, etc on the roof. I don't know if I would go so far as to call them green roofs... but it was very common to have LARGE trees etc up on the upper floors. Why haven't developers caught on to this here?

I believe that's the difference between what's called intensive vs extensive green roofs. If I remember correctly, intensive roofs can accommodate trees, shrubbery, etc, while extensive is just for grasses. Much different engineering requirements behind the two, and also much different uses.

I noticed in Toronto that many of the condo buildings have large trees, shrubs, etc on the roof. I don't know if I would go so far as to call them green roofs... but it was very common to have LARGE trees etc up on the upper floors. Why haven't developers caught on to this here?

I noticed in Toronto that many of the condo buildings have large trees, shrubs, etc on the roof. I don't know if I would go so far as to call them green roofs... but it was very common to have LARGE trees etc up on the upper floors. Why haven't developers caught on to this here?